FDA grants breakthrough therapy designation to AMT-060 for severe hemophilia B

The FDA granted breakthrough therapy designation to AMT-060 for the treatment of severe hemophilia B, according to the agent’s manufacturer.

AMT-060 (uniQure) is an investigational gene therapy.

“We are very pleased the FDA has designated AMT-060 a breakthrough therapy for patients with hemophilia B,” Matthew Kapusta, CEO of uniQure, said in a company-issued press release. “The FDA’s decision to prioritize and expedite the review of AMT-060 is an important milestone for uniQure, and we are committed to working closely with the FDA to rapidly advance our hemophilia B program into late-stage development.”

Results of an ongoing, dose-ranging phase 1/phase 2 study of AMT-060 in patients with severe hemophilia B showed treatment was associated with sustained increases in Factor IX, reductions in Factor IX replacement usage, and a near cessation of spontaneous bleeding at up to 12 months of follow-up.

The data — presented in December at the ASH Annual Meeting and Exposition — included up to 52 weeks of follow-up in a low-dose cohort (n = 5) and up to 31 weeks of follow-up in a second-dose cohort (n = 5).

All five patients in the second-dose cohort showed a dose response with improvement in disease state. All four patients who previously required chronic replacement therapy discontinued precautionary Factor IX infusions.

All five patients in the low-dose cohort — whose bleedings were previously uncontrolled despite prophylactic therapy — continued to maintain constant and clinically meaningful levels of Factor IX activity for up to 52 weeks after treatment with AMT-060. This resulted in a complete cessation of spontaneous bleedings in the last 14 weeks of observation, according to the press release.

Three patients experienced mild, asymptomatic elevations of alanine aminotransferase. However, no severe adverse events occurred. No patients in either cohort developed inhibitory antibodies against Factor IX.